Heretofore, as a slide guiding device for a movable slide as used in machine tools or the like, there has been known one which is provided with a slide guiding surface formed on a support member such as bed or the like and a sliding surface which is formed on a movable slide such as column, saddle, spindle head or the like to be slidable on the slide guiding surface.
In the slide guiding device, the sliding surface has formed thereon oil grooves each with a supply hole for supplying lubrication oil to a contact surface area between the slide guiding surface and the sliding surface, and the lubrication oil is supplied over the whole of the contact surface area by supplying the lubrication oil to the oil grooves, so that sliding resistance can be reduced between the slide guiding surface and the sliding surface.
The aforementioned background art is a conventional art, and the inventors of this application have not known any particular reference which describes a background art relevant to the present invention.
In the aforementioned conventional slide guiding device, the lubrication oil supplied from the oil grooves of the sliding surface flows out of the sliding surface and the slide guiding surface to decrease at these surfaces as the sliding surface is slidden on the slide guiding surface. Thus, the lack of the lubrication oil takes place at a contact surface area between the sliding surface and the slide guiding surface. This causes the slide guiding device to generate many lost motions, whereby a problem arises in that there take place deterioration in the feed accuracy of the slide guiding device and excessive abrasion or wear of either or both of the sliding surface and the slide guiding surface. To avoid this, it has been a practice that an additional oil supply facility for supplying lubrication oil is provided to supply lubrication oil of a predetermined quantity at a predetermined time interval or each time of a predetermined number of sliding motions so that the lack of the lubrication oil is prevented from taking place.
However, in order to prevent the lack of the lubrication oil from taking place in the slide guiding device, it has been a practice to cope with the aforementioned problem by shortening the time interval for lubrication oil supply or increasing the oil quantity per supply operation. This gives rise to problems that an oil reservoir for storing the lubrication oil has to be made to be large due to an increase in consumption of the lubrication oil and that the oil supply facility is unavoidable to be enlarged in dimension with a resultant increase in a space to install the oil supply facility. Besides, another problem arises in that an increase in the lubrication oil consumption causes an increase in the running cost for the slide guiding device.
To avoid this, it may be conceived to lower the running cost and to downsize the oil supply facility by lengthening the time interval for lubrication oil supply to reduce the lubrication oil consumption. However, lengthening the time interval for lubrication oil supply or decreasing the oil quantity per supply operation results in an additional problem that the lack of the lubrication oil becomes liable to take place.
To cope with this problem, as shown in FIG. 6, there have been proposed various kinds of lubrication oils whose ingredients are mixed so that the lack of the lubrication oil hardly takes place even where the time interval for lubrication oil supply is lengthened. In a machine tool for precise machining, it is desirable to make the lost motion in a slide guiding device as small as less than 10 μm (ten micron meters). Even where there was used any lubrication oil which meets the requirement, the supply time interval had to be set as short as about two and half (2.5) minutes, and the consumption of the lubrication oil could not be reduced, whereby it was unable to solve the problem which caused an increase in the running cost.
Generally, in conventional slide guiding devices, when a sliding surface being stationary on a slide guiding surface begins to slide, the state of friction is changed from static friction to dynamic friction, whereupon a feed device for driving a sliding surface is slightly deformed, and the slight deformation of the feed device causes the lost motion in the sliding movement of a movable slide. There is an inclination that the larger the friction resistance becomes, the larger the amount of the lost motion becomes. Further, the lost motion is generated by a backlash such as a play in the feed device.
On the other hand, where a scraper finishing by manual work of a skilled worker is carried out on the slide guiding surface and the sliding surface, a fine uneven surface which is unable to machine by machining can be formed on each of the slide guiding surface and the sliding surface, so that it can be realized to make lubrication oil remain on the slide guiding surface and the sliding surface for a long period of time. However, this needs not only the manual work of the skilled worker but also many man-hours for the work, thereby resulting in a substantial increase in the manufacturing cost for the slide guiding device.